Container for liquids



June 16, 1964- A. R. REIN. ETAL CONTAINER FOR uqums Filed May 4, 1961 INVENTORS. ABA/0L0 EOBEPTEf/N 650565 0.5441? 5698052259 BY Hw M United States Patent 3,137,432 CONTAINER FOR LIQUIDS Arnold Robert Rein, Barrington, and George Oscar Schroeder, Palatine, 11]., assignors to American Can Company, New York, N.Y., a corporatio'n of New Jersey Filed May 4, 1961, Ser. No. 107,720 6 Claims. (Cl. 229-31) The present invention relates to a laminated container structure for holding liquids, and in particular to a liquidtight laminated container for liquids wherein the laminated construction is composed principally of fibrous material such as fibreboard, paper and the like.

Because of their low cost, containers composed principally of fibrous materials such as paper and paperboard, are well suited for the marketing of many liquids such as milk, juices, and the like. Obviously for such use, these containers must be liquid-tight. Also, when so used, these containers are filled by the particular packer on automatic equipment, transported often great'distances by commercial carriers, and retailed in a mass market. This procedure involves a great deal of handling, often rough handling, thereby necessitating a fair degree of strength in the containers. Since many of the products marketed in this type of container are for human consumption, an additional requirement of the container is that it maintain the product in a reasonably sterile and uncontaminated condition.

In the past these products have been marketed principally in waxed fibreboard containers. While such containers have been commercially adequate, the manufacturers thereof have always striven to improve their strength, particularly their resistance to abuse. Further, eliminating the flaking of wax from the inside surface of the container into the product has been the subject of continuing research.

One means of improving the strength of the container and obviating wax contamination has been to increase the thickness of fibreboard used and eliminate the use of wax entirely by laminating a moisture impervious plastic film such as polyethylene to both sides of the fibreboard. The greater thickness of fibreboard used increases the cost of such container construction. Further, forming seam seals for such a polyethylene coated container requires special equipment and procedures. The standard machinery presently in use for the manufacture of wax coated fibre containers is not adequate for the commercial production of these plastic coated fibre containers.

It is, therefore, an object of the present invention to provide a liquid-tight container composed principally of fibre, having increased strength for the packing, transportation, and retailing of liquid products.

Another object is to provide a relatively high strength container for liquids composed principally of fibre, wherein substantially no wax or wax-like material will enter the packed product upon abuse of the container.

Still a further object is to provide a liquid-tight, relatively high strength container composed principally of fibre, which can be manufactured on existing equipment for the manufacture of waxed fibre containers. .I

A further object is to provide a liquid-tight, relatively high strength container composed principally of fibre which has an attractive, easily decorated external appearance.

Still another object is to provide a liquid-tight relatively high strength container composed principally of fibre, which is relatively inexpensive to manufacture.

Numerous other objects and advantages of the inven tion will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring tothe drawings:

FIGURE 1 is a perspective View of a container embodying the present invention and illustrating the same in a closed and sealed condition; and

FIG. 2 is a fragmentary enlarged sectional view taken substantially along a vertical plane indicated by lines 2-2 in FIG. 1; and

FIG. 3 is a fragmentary enlarged sectional detail drawn to a different scale taken substantially along a vertical plane indicated by lines 3-3 in FIG. 1.

The container in the instant invention has the general construction and appearance of that shown in US. Patent 2,085,979, issued to J. M. Hothersall. Following this general construction, the container is composed of a body member A, a bottom end B, and a top end C having a closure D mounted thereon. To accomplish the aforementioned objects, the body A, designating from the inside surface to the outside surface of a wall thereof, has: a layer of wax or Wax-like material, a first fibre layer impregnated with the wax or wax-like material; a thermoplastic barrier and adhesive layer; a second fibre layer having a thickness substantially equal to or less than that of the fibreboard layer; and a thermoplastic outer protective coating. The top end C has a similar construction to that of the body, i.e., five layers bonded together. The bottom end B and the closure D may have the same construction as the body and top end, or may be composed of only. three layers, i.e., an inner wax layer, a layer of wax impregnated fibre, and an outer protective coating of thermoplastic film.

As a preferred or exemplary embodiment of the invention, the body A is of tubular configuration having a square or rectangular cross-section. The body A is formed from a flat blank (not shown) folded to form four wall panels, two of which 10, 11 are shown in FIG. 1. The marginal edgesof the blank are overlapped and adhesively bonded by any suitable means to form a longitudinally extending side seam 12. As will be explained more fully hereinafter, the outer surface of the body A is covered with a plastic film 17, one marginal edge of which is within the side seam 12. One means of bonding the side seam'12 is to use this margin of the film 17 as a heat sealable adhesive; or a separate thermoplastic glue may be used as the adhesive.

The wax or wax-like material forms an inner layer 13 and strikes into the adjacent fibre to form a wax impregnated fibreboard ply or layer 14. As is generally true with waxes, the wax or wax-like material constituting the inner layer 13 is a good liquid barrier. In addition to this, the wax used in the instant invention is more flexible, cohesive and adhesive and softer than the wax used in similar prior art fibre containers. These properties of softness, cohesion and adhesion make this wax unsuitable as an outside coating for the fibre containers since they would permit easy sending of the wax and cause blocking or adherence between closely packed containers. However, as an inside coating, these properties insure that substantially no wax flakes off into the packed product.

An example of a wax suitable for the construction of the instant invention is a 50/50 weight mixture of par- .has been found that for any given thickness, wax impregnated fibreboard is substantially stronger than non-impregnated or merely wax coated board. Further, the

thicker than that necessary to provide the container with adequate strength.

Impregnating the fibre with the wax causes the fibreboard layer 14 to have a somewhat translucent greasy appearance. Although a wax impregnated container having such an appearance has the necessary characteristics of liquid tightness and strength, this appearance is considered undesirable and seriously detracts from its marketability. To mask externally this appearance of the wax impregnated fibreboard 14, a second layer of fibre 15 is adhered to the outer surface of the fibreboard layer 14. To join the fibre layer 15 to the fibreboard layer 14, a film or layer of thermoplastic 16 isdisposed therebetween. This thermoplastic layer 16 has a dual function: it provides the adhesive for bonding the fibre layer 15 to the fibreboard layer 14; and it provides a barrier beyond which the impregnating wax can not pass. This latter function is necessary to confine the wax to the fibreboard layer 14 and to keep the fibre layer 15 absolutely free of wax, so that it maintains a pleasing appearance. Therefore, to perform its necessary functions, the thermoplastic layer 16 must be suitable as a fibre-to-fibre adhesive, and must be impervious to wax and wax-like materials. Thermoplastics especially suited for these purposes are polyolefins, and, in particular, polyethylene.

Since the main purpose of the fibre layer 15 is for hiding and appearance, it can be as thin as desired provided it performs its primary function. However, being integrally joined to the impregnated fibrebo-ard layer 14, it can also function to add some structural strength to the wall of the body A. When so functioning, the thickness of the impregnated fibreboard layer 14 can be correspondingly reduced and still provide the container body wall with adequate strength. It has been found, however, that approximately equal thickness of the two fibre plies is the lower limit of thickness of the layer 14 and the upper limit of the layer 15. A thickness of the layer 15 greater than this merely increases the cost of the container without an offsetting advantage; and a thickness of the layer 14 less than this does not have sufiicient fibre to provide the necessary strength after wax impregnation. As a safety factor against excessive abuse, it is preferred to make the main structural member, the impregnated fibreboard ply, substantially thicker than the outer fibre layer 15.

In the preferred embodiment illustrated, the fibre layer 15 is of thin, bleached, substantially white paper approximately the thickness of the wax impregnated fibreboard layer 14. This paper layer by providing the hiding layer for the impregnated fibreboard layer 14, gives the container the external appearance of clean white virgin paper stock. The fibre layer 15 can be decorated with any suitable design or indicia to make an attractive package for retailing.

During the transportation and retailing of the liquid product, the subject container is subjected to external moisture, such as wet icing for refrigeration. To protect the paper ply 15 from deterioration due to these wet conditions, its outer surface is covered by the previously mentioned moisture impervious layer of clear plastic 17. Polyolefins, and in particular polyethylene, are preferred for this outer plastic covering.

The film 17 may be clear or pigmented, or, if suitably treated prior thereto, may have the decoration or indicia applied directly to its surface. If the decoration or indicia is on the outer surface of the protective plastic film 17, the outer surface of the paper layer 15 would be undecorated.

As shown and described in the previously mentioned Hothersall patent, the body A adjacent its upper and 7 lower periphery is bent angularly inwardly, thence'substantially horizontally outwardly, vertically upwardly and downwardly toward the opposite ends of the container, and horizontally inwardly, to provide lower and upper channel 18, 19, respectively. The periphery of the lower and upper ends B and C are adhesively secured within the lower and upper channel 18, 19 respectively by means of a thermoplastic glue or adhesive 20. Since a large and critical portion of the end seals are fibre-to-fibre seals, any standard adhesive suitable for this purpose such as that; presently in use on similar, prior art, Wax-dipped fibrev containers may be usedas the adhesive 20. This fact and the overall similarity of the instant container to the prior wax impregnated fiberboard layer 22 is somewhat thicker than the fibreboard layer 14 of the body A.

The outerplastic film or covering 25 extends into the channel 19-and is secured to the adjacent surface of the channel by means of the glue or adhesive 20. To insure a satisfactory bond between it and the glue 2%, the plastic film 25 is preferably treated by some surface conditioning treatment to make it adherent to the glue. Such surface treatment will also improve the printability of the exposed surface of the film 25. Except for the fibreboard layer 22 which is thicker than its counterpart in the body A,

supported by the bottom end B, the fibreboard ply 27 has.

a thickness greater than the fibreboard ply in either the body A or top end C. i

As with the top end member, to insure a good adhesive seal between the outer surface of the plastic film 28 and.

the glue 20, the film 28 may be given a previous surface conditioning.

Further, since the bottom end B has no barrier layer or outer paper layer to mask the appearance of the wax impregnated fibreboard 27, the outer plastic coating 28 preferably-is pigmented, such as with titanium dioxide to give a pleasing, white external appearance to the bottom B. For best results, the plastic coating 28 contains from 15 to 20% by weight of pigment.

To provide access to the interior of the container, the upper end C is provided with a pouring opening 29, with which is associated a closure D for closing the opening 29 before use, or as a reclosure during use of the container. The closure D is composed of three layers: an

inner wax layer 30; an intermediate wax impregnated portion 33 secured to the container by any suitable means,

such as a staple 34, a recessed center depression 35 which extends into the opening 29, and an outer lip 36 folded over the outer surface of the channel 19 adjacent one corner of the container. After filling, the lower periphery of the depressed portion 35 is expanded outwardly undercontainer for a time sufiicient to impregnate the fibre.

board of each of the body and end members and to form a thin film of wax, or wax-like material, on the inside surface thereof.

Thereafter, the remaining wax; or wax-like material, is drained from the container through the opening 29, permitting the draining, excess wax to run over the inner surface of the closure D. In this manner, the closure D becomes substantially impregnated with wax, and has formed on its inner surface, the layer 30. Thereafter, the container is chilled to set the wax and the opening 29 is closed by means of closure D.

The container is now ready for shipment to a packer. The flushing of the interior of the container with hot wax has a sterilizing effect on the container interior. Since the container is closed while this effect remains, the substantially sterile effect is maintained during shipment to and filling by the packer.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction, and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

We claim: 1. In a leakproof container for liquid products having a tubular container body closed at both ends wherein said body is constructed of laminated material having a plurality of layers, the improvement comprising, said body having, from the inside outwardly:

an inner layer of wax forming substantially the entire interior surface thereof, said wax providing an essentially liquidproof layer;

a layer of wax-impregnated fibreboard, said wax-impregnated fibreboard providing the principal structural strength for said body; 7 a

a layer of thermoplastic resin serving as a barrier layer to prevent penetration of wax beyond said waximpregnated fibreboard layer;

a layer of paper adhesively secured to said wax-impregnated fibreboard by said thermoplastic resin layer and serving as a background for indicia decorating the exterior of said body; v

and an outer layer of polyolefin, said outer layer substantially liquidproofing the exterior surface of said body to prevent liquid seepage into said paper layer.

2. The container as defined in claim 1 wherein said container body is closed at both ends by top and bottom end members secured to the opposite ends of said container body in leakproof end joints.

3. The container as defined in claim 2 wherein the exterior surface of both top and bottom end members, in addition to said body, are coated with a layer of polyolefin.

4. The container as defined in claim 3 wherein the coating of polyolefin applied to the exterior surface of said end members is pigmented with 15% to 20% of titanium dioxide. v

5. A container as set forth in claim 1 wherein said fibreboard is more than twice as thick as said paper.

6. A container as set forth in claim 1 wherein said thermoplastic is a polyolefin.

References Cited in the file of this patent UNITED STATES PATENTS Couch et al. Jan. 2, 1962 

1. IN A LEAKPROOF CONTAINER FOR LIQUID PRODUCTS HAVING A TUBULAR CONTAINER BODY CLOSED AT BOTH ENDS WHEREIN SAID BODY IS CONSTRUCTED OF LAMINATED MATERIAL HAVING A PLURALITY OF LAYERS, THE IMPROVEMENT COMPRISING, SAID BODY HAVING, FROM THE INSIDE OUTWARDLY: AN INNER LAYER OF WAX FORMING SUBSTANTIALLY THE ENTIRE INTERIOR SURFACE THEREOF, SAID WAX PROVIDING AN ESSENTIALLY LIQUIDPROOF LAYER; A LAYER OF WAX-IMPREGNATED FIBREBOARD, SAID WAX-IMPREGNATED FIBREBOARD PROVIDING THE PRINCIPAL STRUCTURAL STRENGTH FOR SAID BODY; A LAYER OF THERMOPLASTIC RESIN SERVINGAS A BARRIER LAYER TO PREVENT PENETRATION OF WAX BEYOND SAID WAXIMPREGNATED FIBREBOARD LAYER; 